Validate operator enum in Query.where() calls

packages/firestore/src/api/database.ts

@@ -70,6 +70,7 @@ import {
   validateOptionalArgType,
   validateOptionalArrayElements,
   validateOptionNames,
+  validateStringEnum,
   valueDescription
 } from '../util/input_validation';
 import * as log from '../util/log';
@@ -1352,8 +1353,10 @@ export class Query implements firestore.Query {
     value: unknown
   ): firestore.Query {
     validateExactNumberOfArgs('Query.where', arguments, 3);
-    validateArgType('Query.where', 'non-empty string', 2, opStr);
     validateDefined('Query.where', 3, value);
+    // Enumerated from the WhereFilterOp type in index.d.ts.
+    const whereFilterOpEnums = ['<', '<=', '==', '>=', '>', 'array-contains'];
+    validateStringEnum('Query.where', whereFilterOpEnums, 2, opStr);
     let fieldValue;
     const fieldPath = fieldPathFromArgument('Query.where', field);
     const relationOp = RelationOp.fromString(opStr);

packages/firestore/src/util/input_validation.ts

@@ -14,7 +14,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 import { fail } from './assert';
 import { Code, FirestoreError } from './error';
 import * as obj from './obj';
@@ -292,6 +291,30 @@ export function validateNamedOptionalPropertyEquals<T>(
   }
 }
 
+/**
+ * Validates that the provided argument is a valid enum.
+ *
+ * @param functionName Function making the validation call.
+ * @param enums Array containing all possible values for the enum.
+ * @param position Position of the argument in `functionName`.
+ * @param argument Arugment to validate.
+ */
+export function validateStringEnum<T>(
+  functionName: string,
+  enums: string[],
+  position: number,
+  argument: unknown
+): void {
+  if (!enums.some(element => element === argument)) {
+    throw new FirestoreError(
+      Code.INVALID_ARGUMENT,
+      `Invalid value ${valueDescription(argument)} provided to function ` +
+        `${functionName}() for its ${ordinal(position)} argument. Acceptable ` +
+        `values: ${enums.join(', ')}`
+    );
+  }
+}
+
 /** Helper to validate the type of a provided input. */
 function validateType(
   functionName: string,

packages/firestore/test/integration/api/validation.test.ts

@@ -800,6 +800,14 @@ apiDescribe('Validation:', persistence => {
       );
     });
 
+    validationIt(persistence, 'enum', db => {
+      const collection = db.collection('test') as any;
+      expect(() => collection.where('a', 'foo' as any, 'b')).to.throw(
+        'Invalid value "foo" provided to function Query.where() for its second argument. ' +
+          'Acceptable values: <, <=, ==, >=, >, array-contains'
+      );
+    });
+
     validationIt(
       persistence,
       'with null or NaN non-equality filters fail',